Electroencephalographic monitoring of brain activity during cardiac arrest: a narrative review

BACKGROUND: To date cardiac arrest (CA) remains a frequent cause of morbidity and mortality: despite advances in cardiopulmonary resuscitation (CPR), survival is still burdened by hypoxic–ischemic brain injury (HIBI), and poor neurological outcome, eventually leading to withdrawal of life sustaining treatment (WLST). The aim of CPR is cardiac pump support to preserve organ perfusion, until normal cardiac function is restored. However, clinical parameters of target organ end-perfusion during CPR, particularly brain perfusion, are still to be identified. In this context, electroencephalography (EEG) and its derivatives, such as processed EEG, could be used to assess brain function during CA. OBJECTIVES: We aimed to review literature regarding the feasibility of EEG and processed or raw EEG monitoring during CPR. METHODS: A review of the available literature was performed and consisted of mostly case reports and observational studies in both humans and animals, for a total number of 22 relevant studies. RESULTS: The research strategy identified 22 unique articles. 4 observational studies were included and 6 animal testing studies in swine models. The remaining studies were case reports. Literature regarding this topic consists of conflicting results, containing studies where the feasibility of EEG during CPR was positive, and others where the authors reached opposite conclusions. Furthermore, the level of evidence, in general, remains low. DISCUSSION: EEG may represent a useful tool to assess CPR effectiveness. A multimodal approach including other non-invasive tools such as, quantitative infrared pupillometry and transcranial Doppler, could help to optimize the quality of resuscitation maneuvers.